Like many other Asian cultures, close relationships and affectionate behavior in public between people of the same sex is very common and accepted. But such relationships are not necessarily gay. Still, sexual relationships between men are assumed to be quite common and accepted, so long as they are kept private.
There is no "scene" in the western style, since being overtly gay is still not acceptable. There are, however, many places for gay people to meet, especially in Hanoi.